123-MIBG DETECTS NEUROBLASTOMA AND PHEOCHROMOCYTOMA

NEW YORK (Reuters Health) Apr 22 - 123I-mIBG scintigraphy is highly sensitive and specific for neuroblastoma and pheochromocytoma, according to a meta-analysis published online April 14th in The Journal of Clinical Endocrinology & Metabolism.

Patients with these tumors have been assessed with radiolabelled meta-iodobenzylguanidine (mIBG) for more than 20 years, lead author Dr. Arnold F. Jacobson told Reuters Health by e-mail. The 123I isotope was approved in Europe and Japan more than 10 years ago and in the US in 2008. The International Neuroblastoma Risk Group includes 123I-mIBG imaging in its recommendations for assessing children with neuroblastoma, Dr. Jacobson said.

He and his colleagues at GE Healthcare, Princeton, New Jersey, performed their meta-analysis "to provide companion and comparison data" to results of a randomized trial published last year. The results of the meta-analysis (and the prospective trial) are consistent with clinical experience, he said.

They included 22 studies (but not last year's randomized trial). Seven studies with 223 patients focused on the diagnostic performance of 123I-mIBG as an imaging agent for neuroblastoma, and 15 studies with 395 patients focused on pheochromocytoma.

Mean quality scores were 85% for the neuroblastoma articles and 76% for the pheochromocytoma articles.

The combined sensitivity of 123I-mIBG for detecting neuroblastoma was 97% and for detecting pheochromocytoma was 96%.

The combined specificity of 123I-mIBG for detecting pheochromocytoma was 98%, but none of the seven articles about neuroblastoma met the eligibility criteria for the analysis of specificity.

Use of the random-effect model to account for the heterogeneity among pheochromocytoma studies yielded slightly lower sensitivity (94%) and specificity (92%).

"Because many of the published studies were retrospective and relatively small, there is the potential for bias in the data," Dr. Jacobson said. "We believe that the meta-analysis results represent the maximum performance characteristics for the imaging method, and in clinical practice, the results would probably be a few percent lower."

J Clin Endocrinol Metab 2010.